1. Related Applications
This application relates to our copending U.S. application Ser. No. 07/329,136 filed Mar. 27, 1989 entitled "Dual Operating System Computer", now abandoned.
2. Field of the Invention
The present invention relates to a mainframe computer system that is operable on one of two distinctly different operating systems. More particularly, the present invention relates to apparatus for enhancing the operation of the operating system which is different from the preferred operating system for which the dual operating system computer was originally designed.
3. Description of the Prior Art
Compilers and emulators are well known and are generally used as black box systems for converting operating instructions form one format into another format which is usable by different computing systems.
Compilers and emulators have been respectively classified in U.S. Class 395, sub-classes 700 and 500 with dual mode operating system computers and micro programmed computers which have alterable stored micro routines utilized to emulate different computers or computing systems. Such computing systems are discussed in the micro programmable CPU described in U.S. Pat. No. 4,199,811 which has been assigned to the same assignee as the present invention. This prior art reference discusses the reasons that cause micro programmed emulators to be generally slower than an emulated computing system which offers a desirable yet complex solution.
A desirable, and more expensive, approach to emulation is found in the IBM AS400 computing system which operates on two distinctly different operating systems. Such Dual Operating System computers require a new architecture different from either previous architectures or systems being merged together and operate on a single new operating system. A variation of such merged operating systems is described in U.S. Pat. No. 4,747,040 issued to AT&T. This dual mode operating system computer supports UNIX.RTM. and MSDOS.RTM. operating systems in a multi-tasking computer system. The MS-DOS operating systems and its applications are executed in a real or non-protected mode and the UNIX applications are executed by the UNIX operating system in a protected mode to prevent conflicting attempts to access the same peripheral device or to write in the same regions of the main memory. To prevent such conflicts, special merged support hardware needs to be provided.
In our aforementioned application Ser. No. 07/329,136 now abandoned, there is described a dual operating system computer which is conditioned to run user programs on one operating system by loading unique microcode in the instruction processor for its associated operating system and then loading the associated operating system in the main memory. Effectively, this application by use of microcode converts one architecture computing system into a second and different architecture computing system.
It would be desirable to provide an improvement of the aforementioned application Dual Operating System Computer which will more efficiently operate programs designed for operation on the mainframe computing system when loaded with its associated operating system. It would be further desirable to provide the dual operating system computer with apparatus which substantially reduces the amount of microcode required to make the architecture conversion. It would be desirable to improve both the performance and speed of operation of the operating system and its user programs and have the hardware enhancement automatically make the operating system conversion as a result of loading the microcode and operating system without supplemental operations.